Deformation of Ni–Mn–Ga martensite under the conditions of ultrasonic resonance
|Victor Lvov 1,2, Sergey Kustov 1, Eduard Cesari 1|
1. Dept. de Física, Universitat de les Illes Balears (UIB), Palma de Mallorca E-07122, Spain
A strong effect of the alternate mechanical stress on the process of magnetically/mechanically induced deformation (MID) of Ni–Mn–Ga martensite has recently been reported in the frequency range from 30 Hz to 10 kHz , being well below the longitudinal resonance frequency of the samples used ~ 100 kHz. To carry out the resonance ultrasonic experiments in the Ni–Mn–Ga martensite under magnetic field or/and axial mechanical stress is an issue of the day and the present communication is aimed at the stimulation of such experiments. To this end, the process of deformation of rod-shaped twinned specimens affected by standing ultrasonic waves and slowly increasing field/stress has been studied in the framework of a statistical model of MID . The additional deformation of the Ni–Mn–Ga specimen activated by the ultrasound in the presence of magnetic field or axial stress has been computed for several realistic values of wave amplitude and the actual values of Young elastic modulus, specimen length, and threshold field/stress (i.e. the field/stress, which "switches on" the process of MID). The decrease of the threshold field/stress under the influence of ultrasound is described quantitatively. It has been shown, in particular, that ultrasonic waves with a strain amplitude equal to 4*10-5 cause a ~ 30% decrease of the threshold field/stress value; the additional deformation induced by the wave reaches its maximal value ~ 2.5% when the field/stress reaches the initial (i.e. obtained in the absence of ultrasound) threshold value. The slow evolution of MID in the stationary magnetic due to switching on the ultrasound has also been modeled. References: . B.W. Peterson, J. Feuchtwanger, J.M. Chambers, D. Bono, S.R. Hall, S.M. Allen, R.C. O’Handley, J. Appl. Phys., 95 (2004) 6963-6964. . V.A. L’vov, O. Rudenko, N. Glavatska, Phys. Rev., B 71 (2005) 024421-6.
Presentation: Poster at E-MRS Fall Meeting 2007, Symposium E, by Victor Lvov
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-10 15:33 Revised: 2009-06-07 00:44